Initial studies on the acquisition of two Spanish copulas, "ser" and "estar", emerged from a research agenda exploring whether second language (L2) development was driven by universal mechanisms manifested in stages rather than an accumulation of entities (Rutherford, 1987). Concerning the Spanish copulas, the stages of acquisition through which Spanish L2 learners pass seem--with a few exceptions--to be largely uniform (e.g. "estar" + locative, "ser/estar" + adjective; VanPatten, 1987; Ryan & Lafford, 1992; Geeslin, 2000). Cheng, Lu and Giannakouros provide one of the first studies which partially test the assumption of universality, examining Mandarin Chinese speakers' copula behaviors over different levels of development. The work of Geeslin as well as Cheng, Lu and Giannakouros is valuable not so much because it provides insights into copula development but rather because this work is building a model for predicting the interaction in general terms between aspectual, semantic, and pragmatic factors and the acquisition of both grammatical and lexical L2 phenomena.